The present invention relates to a process for the preparation of novel 5-alkoxy-2-substituted thio-1,3-thiazoline derivatives of general formula(I) (hereinafter, referred to a ("thiazoline derivatives"). More specifically, thiazoline derivatives of general formula(I) of the present invention can be used as herbicide, fungicide or insecticide and as useful intermediates in preparing their derivatives. (Japan Patent No. 85-184,070) ##STR2##
Wherein, R is hydrogen, C.sub.1 -C.sub.6 alkyl, allyl, 2-propynyl, benzyl, and 2-pyridylmethyl and R.sub.1 is methyl and ethyl.
The thiazoline derivative of general formula(I) according to the present invention is a novel compound which is not disclosed in any literatures. However, the process for preparing thiazoline derivatives of general formula(II) similar to that of this invention is disclosed in scientific magazines (J. Org. Chem., 1965, 30, 491 and J. Org. Chem, 1971, 36, 1068) as follows:
2-aminoethyl sulfate of general formula(III) or aziridine derivatives of general formula(IV) is reacted with ethylxanthic acid, potassium salt (EtOCS.sub.2 K) or carbon disulfide respectively to prepare thiazolidine-2-thione of general formula(V). Then, the resulting material is reacted with alkylating agent in the presence of a base to prepare thiazoline derivatives of general formula(II) ##STR3##
Wherein, R is methyl; R' and R" are hydrogen, alkyl or phenyl group.
The inventors attempted to research on the basis of the above-mentioned known process technique in order to prepare thiazoline derivatives of general formula(I) (R is hydrogen) available as useful intermediates of cephalosporin derivatives. That is, in order to prepare thiazoline derivatives of general formula(I), the inventors tried to prepare the compound of general formula (III) or (IV) (R' or R" is alkoxy group) but could not succeed.
The present inventors found that there were many problems in preparing thiazoline derivatives of general formula(I) by the known process and studied continuously to reach a new method. Thus, according to the present invention, dithiocarbamate of general formula (VI) is readily converted into thiazoline derivatives of general formula(I) by intramolecular cyclization. ##STR4##
Wherein, R and R' are defined as the above general formula (I).